They're not links to Facebook, but namespace declarations. It means that the site is using attributes that begin with "fb:". The namespace declaration simply tells the browser that attributes beginning with "fb:" are related to Facebook.

There's only one Doctype in that list. The rest are opening <html> tags that contain a class identifying the version of Internet Explorer. It's a technique that makes it possible to serve special styles to handle bugs or other problems in old versions of IE.

This looks a lot more complicated than it really is. We’re doing a few conditionals here which means we’ll serve an html element with different classes depending on what browser people are using. So for example, if someone using IE7 visits the page (God, help them), the html element will look like this (also dependent the language):

<html lang="en" class="no-js ie7 oldie">

The oldie class is so you can do specific styling on older browsers. So let’s say you have an element that needs a bit of extra padding on top in older versions of IE because it looks off. In your CSS you could have something like this:

.box { padding: 0; }

.oldie .box { padding-top: 3px; }

Only “oldie” browsers would see that extra padding. You could also use the “ie7″ class if you wanted to narrow it down even further.

The no-js class is used in the same way and is used just in case you want to style things when users have javascript turned off.